SV-POW! … All sauropod vertebrae, except when we're talking about Open Access

ASP target of opportunity

July 20, 2009

Weren’t we just discussing the problem of keeping up with all the good stuff on da intert00bz? The other day Rebecca Hunt-Foster, a.k.a. Dinochick, posted a “mystery photo” that is right up our alley here at SV-POW!, but, lazy sods that we are, we missed it until just now. Here’s the pic:

I flipped it 90 degrees so that you can see more clearly what is going on. This is a cut and polished section of a pneumatic sauropod vertebra–the bottom half of the mid-centrum of a dorsal vertebra, to be precise. Cervicals usually have concave ventral surfaces, and sacrals are usually either wider and flatter or narrower and V-shaped in cross sections, so I am pretty confident that this slice is from a dorsal. Compare to the classic anchor cross-section in this Camarasaurus dorsal:

(You may remember this image from Xenoposeidon week–almost two years ago now!)

Naturally as soon as I saw ReBecca’s shard of excellence, I wondered about its ASP, so after a bit of GIMPing, voila:

As usual, bone is black, air is white, and everything else is gray. And the ASP is:

461080 white pixels/(461080 white + 133049 black pixels) = 0.78

So, we know what this is, and we know the ASP of this bit of it, and we can even figure out the in vivo density of this bit. The density of cortical bone ranges from about 1.8 g/cm^3 for some birds to about 2.0 for most mammals. For the sake of this example–and so I can hurry back to writing my lecture about the arse–let’s call it 1.9. The density is then the fraction of bone multiplied by the density of bone, full stop. If it was an apneumatic bone, we’d have to add the fraction of marrow multiplied by the density of marrow, but the density of air is negligible so we can skip that step here. The answer is 0.22 x 1.9 = 0.42 g/cm^3, which is pretty darned light. Keep in mind, though, that some slices of Sauroposeidon (and ‘Angloposeidon’, as it turns out) have ASPs of 0.89, and thus had an in vivo density half that of the above slice (0.11 x 1.9 = 0.21 g/cm^3).

What’s that in real money? Well, your femora are roughly 60% bone and 40% marrow, with a density of ((0.6 x 2.0)+(0.4 x 0.93)) = 1.6 g/cm^3, four times as dense as the bit of vertebra shown above, and eight times as dense as some slices of Sauroposeidon and ‘Angloposeidon’. If that doesn’t make you self-conscious about your heavy thighs, I don’t know what will.

The Other Guy is Michael Collins, who like other Command Module pilots was regularly on the opposite side of the moon from his fellow astronauts and a quarter million miles from everyone else, as isolated by distance as any individual human has ever been.

Says he on the 40th anniversary: “Some things about current society irritate me, such as the adulation of celebrities and the inflation of heroism…in my own case at least, it was 10 percent shrewd planning and 90 percent blind luck. Put LUCKY on my tombstone.”

True story. (I think that there is a brief mention of this in Collins’ autobiography.)

(To fill in a little of the background: I grew up as a “space brat” like some other kids are “army brats”: Thomas R. Holtz, Sr. is an aerospace engineer and worked on the manned space program from Gemini through Apollo-Soyuz. I spent the late ’60s through mid ’70s in Nassau Bay, a suburb of Houston near to Johnson Space Flight Center. Lots of engineers, technicians, and some astronauts lived in the neighborhood.)

They risked their lives and made our closest neighbor a lot more interesting!

I think one of them also paints pictures of the moon landing and mixes actual moon dust into the paint. They sell for 20k at least. Not bad!

And Buzz Aldrin will always be a hero in my book for punching that moon-landing denialist punk in the face a few years back. Whether it’s flat-earthers, gravity catastrophists, creationists, or BANDits, some wackos just don’t know when to stop.